<?php 
$category = New Manager_Model_Category();
?>
<ul>
<?php foreach ($category->getDataParent() as $data): ?>
    <li>
        <a href="#"> <?php echo $data['category_name']."<br>";?> </a>
        <?php
            if(!is_null($category->getDataChildren($data['category_code']))):?>
                 <ul> 
                     <?php foreach($category->getDataChildren($data['category_code']) as $subcat):?>
                     <li>
                         <a href="#">  <?php echo $subcat['category_name'];?> </a>
                     </li>
                    <?php endforeach;?>
                 </ul>
        <?php
        endif;
        ?>
    </li>
<?php endforeach; ?>
</ul>